Among the most important challenges faced by male childhood and adolescent and young adult (AYA) cancer survivors is the reproductive toxicity of cancer chemotherapy. Cisplatin and Ifosfamide form the backbone of chemotherapy for some of the most common childhood and young adult cancers, but there is a gap in knowledge regarding the effects of cisplatin, and the effects of ifosfamide without cyclophosphamide, on spermatogenesis and steroidogenesis in male AYA survivors of childhood cancer and non-germ cell cancer populations. DNA methylation changes are a possible mechanism of action of these drugs on testicular function. A better understanding of these effects will allow for identificationof high risk patients and better prevention strategies for testicular toxicity to be developed for pediatric and AYA cancer treatment protocols. This study will comprehensively evaluate the effects of cisplatin with or without ifosfamide on spermatogenesis and steroidogenesis among childhood and AYA survivors treated with modern chemotherapies for osteosarcoma. Specifically, our aims are: 1) Determine whether infertility and/or biomarkers of spermatogenesis and steroidogenesis differ in male osteosarcoma survivors treated with cisplatin with or without ifosfamide compared to male controls without a history of cancer; 2) Evaluate whether cisplatin with or without ifosfamide for the treatment of osteosarcoma is associated with sperm DNA methylation patterns. Osteosarcoma survivors will be recruited from two COG therapeutic trials [COG AOST0331 and INT0133 (CCG7921 and POG9351)], and controls identified and recruited through address-based sampling. Subjects will complete questionnaires and provide blood, saliva, and semen samples through a mail protocol. Blood samples will be analyzed for testosterone, FSH, LH, Inhibin B; genomic DNA extracted from saliva and stored for future studies of host genetic variation in metabolism of chemotherapeutic drugs storage; and sperm DNA will be assayed using genome-wide methylated DNA immunoprecipitation followed by next generation sequencing. The assembled team and consortium brings together multi-disciplinary expertise in urology, andrology, oncology, epidemiology, biostatistics, and epigenomics. Completion of the proposed research will be a major step towards informing male childhood and AYA cancer patients receiving similar regimens about the adverse effects of their treatment and towards identifying high risk groups that would benefit from targeted strategies for fertility preservation.